Vertical stirring

Novolen A process for making polypropylene in the gas-phase, using a vertical stirred-bed reactor. Developed by BASF and engineered by Uhde. Eight plants had been licensed as of 1985. A metallocene-catalyzed version was introduced in 1996. The name is used also for the product. 

Tumbler, jar, drum, or cannon ball mills Szegvari attritor vertical mills and other vertical stirred ball mills Planetary Fritsch and Retsch model mills Shaker (vibratory) SPEX model mills... 

Szegvari attritor vertical mills and other vertical stirred ball mills... 

Novolen Process (Figure 7) With this technology, which comprises two vertical stirred gas-phase reactors in series, homopolymers as well as impact and random copolymers are produced. The first reactor operates at 80°C and 20-35 bar monomer pressure and is used exclusively for the homopolymerization of propylene. Propylene is injected as a liquid and cools the exothermic polymerization by its... 

Note that the period of vertical stirring of the atmosphere is ss80 days [4]. Thus, those trace gases whose residence time is less than 80 days are distributed non-uniformly in the atmosphere. Examples of such gases are CO, NO., NH3, SO2, etc. In the vicinity of their sources their concentrations and the removal (supply) rates may be higher than the values shown in Table 1. 

Figure 9.8 Vertical stirred media mill. (Reproduced with permission of Union Process, Inc.)...

Further, it has been assumed that the concentrate would require grinding to 90% passing 44 pm for pressure leaching, and 90% passing 20 pm for atmospheric leaching. The additional grinding in a vertical stirred mill is estimated to cost 0.66/t concentrate, or 56,000 per year. 

Three main types of gas-phase reactors are used in the industry fluidized-bed, vertical stirred-bed and horizontal stirred-bed reactors. 

The Novolen process [78], now licensed by Novolen Technology Holdings (NTH), uses the vertically stirred reactor for propylene polymerization. The basic process is similar to the Unipol process but with a simpler polymer discharge system. Novolen claims this process requires the lowest capital investment of its class and has low operating costs. 

The oldest example of this procedure is the manufacture of high-impact polypropylene, as already described (see Section 8.1.2). Other applications have become more popular lately, especially for the production of bimodal resins. Figure 8.36 illustrates a tandem process using two gas-phase vertical stirred-tank reactors. Several other reactor combinations are used industrially [65]. For heterogeneous processes, the first reactor(s) in the series can be either slurry or gas-phase, but commonly the second reactor (or set of reactors) is a gas-phase reactor. This is especially important when the production of polymers with lower crystallinity... 

The core for the production of metallocene-based polymers is the Novolen Gas Phase Process [64] which combines metallocene drop-in technology (Fig. 40). The core of the process is one or two vertical stirred reactors in series. The process can manufacture... 

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